Polyamines containing urea groups and process for their preparation

ABSTRACT

Low-viscosity (cyclo)-aliphatic polyamines containing urea groups and having more than two amino groups may be prepared by reacting (cyclo)aliphatic diamines with polyisocyanates containing isocyanurate groups or biuret groups. Such polyamines are useful as components in PUR reaction finishes and coating and adhesive compositions.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to low-viscosity (cyclo)aliphatic polyamines containing urea groups and having more than 2 amino groups and to a process for their preparation.

2. Discussion of the Background

Low molecular weight (cyclo)aliphatic diamines containing urea groups, and of course particularly higher functional polyamines, are either solid or highly viscous at room temperature and cannot be processed in the absence of a solvent.

However, low-viscosity (cyclo)aliphatic polyamines containing urea groups would be desirable for use in polyurethane (PUR) reaction finishes and also as components in coatings and adhesives. Thus, there is a need for low-viscosity (cyclo)aliphatic polyamines containing urea groups.

SUMMARY OF THE INVENTION

Accordingly, it is one object of the present invention to provide novel polyamines.

It is another object of the present invention to provide novel polyamines which contain urea groups and have a low viscosity.

It is another object of the present invention to provide a process for preparing such polyamines.

It is another object of the present invention to provide novel coating compositions which comprise such a polyamine.

It is another object of the present invention to provide a method for coating a substrate with such a coating composition.

It is another object of the present invention to provide novel adhesives which contain such a polyamine.

It is another object of the present invention to provide a method for adhering two surfaces with such an adhesive.

These and other objects, which will become apparent during the following detailed description, have been achieved by the inventors' discovery that low-viscosity (cyclo)aliphatic polyamines containing urea groups may be obtained by reacting (cyclo)aliphatic diamines with polyisocyanates containing isocyanurate groups or biuret groups.

The present invention thus provides to low-viscosity (cyclo)aliphatic polyamines containing urea groups and having more than two amino groups, obtainable by reacting diamines of the formula (I)

    R.sup.1 --NH--A--NH--R.sup.2                               (I)

where A represents a (cyclo)aliphatic hydrocarbon radical having 2-16C atoms which is optionally C₁₋₄ -alkyl-substituted, R¹ and R² denote H or a radical of the formula ##STR1## and R3 denotes a (cyclo)aliphatic hydrocarbon radical having 1-12C atoms, which is optionally branched,

with polyisocyanates containing isocyanurate and/or biuret groups of the formula (IIa) and (IIb)

    OCN--(B)--[X].sub.n --NCO                                  (IIa)

and

    OCN--(B)--NCO,                                             (IIb),

where B denotes ##STR2## [X]_(n) denotes: ##STR3## and n denotes 1-4 and S indicates a saturated ring, the weight ratio of (IIa) to (IIb) is (100 to 20) to (0 to 80) and 1 to 5 mole of the diamine (I) are used per the total of NCO groups in the compounds of formulae (IIa) and (IIb).

The invention furthermore provides low-viscosity (cyclo)aliphatic polyamines containing urea groups and having more than two amino groups, obtainable by:

(A) reacting diamines of the formula (I)

    NH.sub.2 --A--NH.sub.2                                     (I)

where A represents a (cyclo)aliphatic hydrocarbon radical having 2-16C atoms which is optionally C₁₋₄ -alkyl-substituted,

with polyisocyanates containing isocyanurate and/or biuret groups and of the formula (IIa) and (IIb)

    OCN--(B)--[X].sub.n --NCO                                  (IIa)

and

    OCN--(B)--NCO                                              (IIb),

where B denotes ##STR4## [X]_(n) denotes: ##STR5## and n denotes 1-4, the weight ratio of (IIa) to (IIb) is (100 to 20) to (0 to 80) and 1 to 5 mole of the diamines (I) are used per the total of NCO groups in the compounds of formulae (IIa) and (IIb); and

(B) and then reacting the product with one mole of maleic or fumaric C₁₋₂ -(cyclo)aliphatic hydrocarbyl ester per NH₂ equivalent.

The invention also provides low-viscosity, ureacontaining (cyclo)aliphatic polyamines, which contain inert compounds, such as, for example, plasticizers, in amounts of 5 to 100 parts by weight, based on the weight of the diamine of formula (I).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Thus, thee low-viscosity (cyclo)aliphatic polyamines containing urea groups according to the present invention can be obtained by various processes.

In a first method, when R¹ and R² are hydrogen or a radical of the formula --CH(COR³)CH₂ CO₂ R³, the preparation of the compounds according to the present invention is carried out by reacting the compounds of formulae (I) and (II) in a molar ratio of 1:1 to 5:1, the polyisocyanate of formula (II) being added in portions to the diamine of formula (I) which is heated to 100°-190° C., with thorough stirring and blanketing with nitrogen. After the end of the polyisocyanate addition, the reaction mixture is heated for about a further 10 minutes. It is then cooled to room temperature.

In a second method for the preparation of the polyamines according to the present invention, the polyamines produced by the first method in which R¹ and R² are hydrogen are reacted as follows. The reaction mixture is cooled to room temperature and is reacted with a maleic or fumaric C₁₋₂ -(cyclo)aliphatic hydrocarboyl ester so that 1 mole of maleic or fumaric ester is reacted per 1 NH₂ equivalent at 50° to 70° C.

The compounds according to the present invention--the reaction products of the compounds of formulae (I) and (II)--are characterized by an amine content of 1-4 mmol/g, by an isocyanurate group content of 1-6 % (based on 126 g/mol) or by a biuret group content of 1-5 % (based on 98 g/mol). Their viscosity at 25° C. can be varied within a wide range. It is 100-10⁵ mPa.s, depending on the ratio of NH equivalents to NCO equivalents.

The diamines of formula (I) used for the preparation of the polyamines according to the present invention have long been known and do not form a subject of the present invention. They are obtained by reacting the diamines H₂ N--A--NH₂ and maleic or fumaric esters, 0.5 mole of diamine being reacted in a known manner per mole of maleic or fumaric ester. The diamines H₂ N--A--NH₂ are aliphatic or cycloaliphatic diamines, such as, for example, 1,6-diaminohexane, 2-methyl-1,5-diaminopentane 2,2,4(2,4,4)-trimethyl-1,6 diaminohexane (TMD), 2,4'- and/or 4,4'-diaminodicyclohexylmethane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,4- and 1,2-diaminocyclohexane, m-hexahydroxylylenediamine, 1-amino-3,5,5-trimethyl-5-aminomethylcyclohexane (isophoronediamine, abbreviated to IPD).

The polyisocyanates which are suitable for the preparation of the polyamines according to the present invention are polyisocyanates containing isocyanurate or biuret groups. The preparation of these isocyanuratoisocyanates is described in German Offenlegungsschrift 23 25 826, 26 44 684, 28 21 109 and 29 16 301. They are prepared by partial trimerization of the diisocyanate with the aid of a catalyst--the quaternary ammonium salts described in German Offenlegungsschrift 29 16 201 have proved most suitable--and subsequent separation of the unconverted diisocyanate by thin-film distillation from the reaction product, the polyisocyanate containing isocyanurate groups. As a rule, the monomer-freed isocyanuratoisocyanates are used for the reaction of the diamines with the isocyanuratoisocyanates by the process according to the invention. In some cases, it has proved expedient to use the partially trimerized diisocyanate mixture without separating the unconverted diisocyanate beforehand. The polyisocyanates which contain biuret groups and are suitable according to the invention are described in German Offenlegungsschrift 23 08 015. They are prepared by reacting water with excess diisocyanate, the unconverted diisocyanate being separated by thin film distillation after biuret formation is complete. The same applies here as in the case of the polyisocyanates containing isocyanurate groups. As a rule, the monomer-freed polyisocyanate containing biuret groups is used; in some cases, however, removal of diisocyanate may be dispensed with.

The compounds according to the invention are outstandingly suitable for the preparation of PUR reaction finishes, coatings and adhesives, the curing of which is effected at room temperature or slightly elevated temperature, as a rule 80° C. The coatings and adhesives of the present invention will typically contain, in addition to the polyamine of the present invention, a curing agent such as hydroxy-functional polyesters and acrylic resins. PUR coatings are described in Kirk-Othmer, Encyclopedia of Chemical Technology, 4th Ed., Wiley, N.Y., vol. 6, pp. 686-690 (1993), which is incorporated herein by reference.

Other features of the invention will become apparent in the course of the following descriptions of exemplary embodiments which are given for illustration of the invention and are not intended to be limiting thereof.

EXAMPLES A.1. Reaction Products of 1 Mole of Diamine and 2 Moles of Maleic Ester General Preparation Method

1 mole of diamine is added dropwise to 2 moles of maleic or fumaric ester at 50°-60° C. in such a way that the temperature of the reaction mixture does not exceed 70° C. After the end of the diamine addition, heating is continued for about a further 2 hours at 60° C. to complete the reaction. A further treatment (distillation) of the reaction mixture is not required for the further reaction with the polyisocyanate.

                                      TABLE 1                                      __________________________________________________________________________     Composition                          NH.sub.2                                                                            Viscosity                            No.                                                                               Diamine (1 mol)       Maleic ester (2 mol)                                                                       mmol/g                                                                              at 25° C. mPa ·                                                s                                    __________________________________________________________________________     1  IDP                   Diethyl maleate                                                                            3.77 340                                  2  IDP                   Dibutyl maleate                                                                            3.12 165                                  3  IDP                   Di-2-ethylhexyl maleate                                                                    2.26 126                                  4  TMD                   Diethyl maleate                                                                            3.89 100                                  5  TMD                   Dibutyl maleate                                                                            3.17 95                                       ##STR6##             Diethyl maleate                                                                            4.05 870                                  7                                                                                  ##STR7##             Dibutyl maleate                                                                            3.28 730                                  8                                                                                  ##STR8##             Diethyl maleate                                                                            3.56 1200                                 9                                                                                  ##STR9##             Dibutyl maleate                                                                            2.92 1080                                 __________________________________________________________________________

A.2. Polyisocyanates Polyisocyanate 1

Commercial isocyanuratoisocyanate based on isophorone diisocyanate having an NCO content of 17.2%.

Polyisocyanate 2

Commercial isocyanuratoisocyanate based on hexamethylene diisocyanate having an NCO content of 21%.

Polyisocyanate 3

Commercial biuret based on hexamethylene diisocyanate having an NCO content of 22.9%.

B.1. Examples 1 to 11 Compounds According to the Invention (Reaction: A.1.+A.2.) General Preparation Method

The polyisocyanate is added in portions, in the course of about 0.5 hour, to the disecondary diamine heated to 100° to 150° C., with thorough stirring and blanketing with nitrogen. After the end of the polyisocyanate addition, the mixture is immediately cooled to room temperature.

                                      TABLE 2                                      __________________________________________________________________________     Composition               NH:NCO--       Visc. at                              Example                                                                             Parts                                                                              Diamine                                                                             Parts                                                                              Polyisocyanate                                                                         ratio as number                                                                        NH.sub.2 content                                                                      25°                            No.  by wt.                                                                             (A.1.)                                                                              by wt.                                                                             (A.2)   of equivalents                                                                         mmol/g mPa · s                      __________________________________________________________________________     1    70  No. 4                                                                               30  No. 1   2.26:1  1.51   10,000                                2    80  No. 4                                                                               20  No. 2   2.18:1  2.12   16,000                                3    90  No. 4                                                                               10  No. 2   7.17:1  3.02    1,300                                4    90  No. 4                                                                               10  No. 1   8.37:1  3.10    1,850                                5    80  No. 1                                                                               20  No. 2   3.11:1  2.08   21,000                                6    90  No. 1                                                                               10  No. 2   7:1     3.0    10,500                                7    92.6                                                                               No. 2                                                                               7.4 No. 2   7.8:1   2.4     2,780                                8    86.3                                                                               No. 2                                                                               13.7                                                                               No. 2   3.89:1  1.95   16,500                                9    90  No. 5                                                                               10  No. 1   7.15:1  2.46     740                                 10   90  No. 7                                                                               10  No. 1   7.3:1   2.55    1,730                                11   90  No. 9                                                                               10  No. 1   6.59:1  2.35    1,700                                __________________________________________________________________________

B.2. Examples 12 to 25 Compounds According to the Invention (Reaction Products of Diamines and Polyisocyanates (A.2.)) General Preparation Method

The polyisocyanate is added in portions, with thorough stirring and blanketing with nitrogen, to the diamine heated to 150°-180° C., in a manner such that the temperature of the reaction mixture does not exceed 190° C. After the end of the polyisocyanate addition, heating is continued for about a further 10 minutes. The reaction is then complete.

                                      TABLE 3                                      __________________________________________________________________________     Example                                                                             Composition                         NH.sub.2 content                                                                      Viscosity                      No.  Parts by wt.                                                                          Diamine      Parts by wt.                                                                          Polyisocyanate                                                                          mmol/g at 25° C. mPa                                                           · s                   __________________________________________________________________________     12   500    IPD          100    Polyisocyanate 1                                                                        9.15   920                            13   500    IPD          125    Polyisocyanate 1                                                                        8.32   3,200                          14   500    IPD          150    Polyisocyanate 1                                                                        7.60   23,700                         15   500    TMD          100    Polyisocyanate 1                                                                        9.61   43                             16   500    TMD          150    Polyisocyanate 1                                                                        8.31   180                            17   500    TMD          200    Polyisocyanate 1                                                                        7.48   1,130                          18   500    TMD          250    Polyisocyanate 1                                                                        6.71   5,900                          19   500    IPD          100    Polyisocyanate 1                                                                        8.01   4,650                          20   500    IPD          125    Polyisocyanate 1                                                                        7.80   11,500                         21   500                                                                                    ##STR10##   100    Polyisocyanate 1                                                                        13.5   100                            22   500                                                                                    ##STR11##   200    Polyisocyanate 1                                                                        11.18  100                            23   500                                                                                    ##STR12##   300    Polyisocyanate 1                                                                        9.27   870                            24   500                                                                                    ##STR13##   400    Polyisocyanate 1                                                                        7.77   26,000                         25   500    IPD          160    Polyisocyanate 2                                                                        7.38   39,000                         __________________________________________________________________________

B.3. Examples 26 to 31 Compounds According to the Invention (Reaction Products of B.2.+Maleic Ester) General Preparation Method

The preparation of the compounds according to the invention is carried out analogously to the preparation of the compounds described in A.1., 1 amine equivalent of the amines B.2. being reacted per mole of maleic or fumaric ester.

                                      TABLE 4                                      __________________________________________________________________________            Composition                                                                           Polyamine                NH.sub.2 content                                                                      Viscosity at 25° C.       Example No.                                                                           Parts by wt.                                                                          Example No. (B.2.)                                                                       Parts by wt.                                                                          Maleic ester                                                                           mmol/g mPa · s                 __________________________________________________________________________     26     133.6  6         172    Diethyl maleate                                                                        3.27   1,100                            27     120    16        172    Diethyl maleate                                                                        3.42     900                            28     120    16        228    Dibutyl maleate                                                                        2.87     400                            29     132    14        228    Dibutyl maleate                                                                        2.78   1,200                            30     132    14        172    Diethyl maleate                                                                        3.29   7,500                            31     132    24        228    Dibutyl maleate                                                                        2.80     480                            __________________________________________________________________________

The present application is based on German Patent Application P 44 39 421.7 filed on Nov. 4, 1995, which is incorporated herein by reference in its entirety.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. 

What is claimed as new and is desired to be secured by Letters Patent of the United States is:
 1. A low-viscosity (cyclo)aliphatic polyamine containing urea groups and having more than two amino groups, obtained by reacting a diamine of the formula (I):

    R.sup.1 --NH--A--NH--R.sup.2                               (I)

wherein A is a (cyclo)aliphatic hydrocarbon radical having 2-16 carbon atoms which is optionally C₁₋₄ -alkyl-substituted, R¹ and R² are H or a radical of the formula ##STR14## wherein R³ is a (cyclo)aliphatic hydrocarbon radical having 1-12 carbon atoms, which is optionally branched, with polyisocyanates containing isocyanurate and/or biuret groups and of the formula (II):

    OCN--(B)--[X].sub.n --NCO                                  (IIa)

and

    OCN--(B)--NCO                                              (IIb),

wherein B is ##STR15## [X]_(n) is: ##STR16## and n is 1-4, the weight ratio of (IIa) to (IIb) is (100 to 20) to (0 to 80) and 1 to 5 moles of the diamine (I) are reacted per the total moles of NCO groups in the compounds of formulae (IIa) and (IIb).
 2. The polyamine according to claim 1, which contains 0.01 to 5 parts by weight of an inert compound.
 3. The polyamine according to claim 2, which contains a plasticizer.
 4. A low-viscosity (cyclo)aliphatic polyamine containing urea groups and having more than two amino groups, obtained by:(A) reacting a diamine of the formula (I):

    NH.sub.2 --A--NH.sub.2                                     (I)

wherein A is a (cyclo)aliphatic hydrocarbon radical having 2-16 carbon atoms which is optionally C₁₋₄ -alkyl-substituted, with polyisocyanates containing isocyanurate and/or biuret groups and of the formula (II):

    OCN--(B)--[X].sub.n --NCO                                  (IIa)

and

    OCN--(B)--NCO                                              (IIb),

wherein B is ##STR17## [X]_(n) denotes: ##STR18## and n is 1-4, the weight ratio of (IIa) to (IIb) is (100 to 20) to (0 to 80) and 1 to 5 moles of the diamine (I) are reacted per the total of NCO groups in the compounds of formulae (IIa) and (IIb); and (B) reacting the product with one mole of maleic or fumaric C₁₋₁₂ -(cyclo)aliphatic hydrocarbyl ester per NH₂ equivalent.
 5. The polyamine according to claim 4, which contains 0.01 to 5 parts by weight of an inert compound.
 6. The polyamine according to claim 5, which contains a plasticizer.
 7. A process for the preparation of a low-viscosity (cyclo)aliphatic polyamine containing urea groups, said process comprising:reacting a diamine of formula (I):

    R.sup.1 --NH--A--NH--R.sub.2                               (I)

wherein A is a (cyclo)aliphatic hydrocarbon radical having 2-16 carbon atoms which is optionally C₁₋₄ -alkyl-substituted and R¹ and R² are H or a radical of the formula ##STR19## wherein R³ is a (cyclo)aliphatic hydrocarbon radical having 1-12 carbon atoms, which is optionally branched, with polyisocyanates containing isocyanurate and/or biuret groups of formulae (IIa) and (IIb):

    OCN--(B)--[X].sub.n --NCO                                  (IIa)

and

    OCN'(B)--NCO                                               (IIb),

wherein B is ##STR20## [X]_(n) is: ##STR21## the weight ratio of (IIa) to (IIb) is (100 to 20) to (0 to 80) and 1 to 5 mole of the diamine (I) are reacted per the total of NCO groups in the compounds of formulae (IIa) and (IIb), at a temperature of 100° to 190° C.
 8. A process for the preparation of a (cyclo)aliphatic polyamine containing urea groups, said process comprising:(A) reacting a diamine of formula (I):

    H.sub.2 N--A--NH.sub.2                                     (I)

wherein A is a (cyclo)aliphatic hydrocarbon radical having 2-16 carbon atoms which is optionally C₁₋₄ -alkyl-substituted, with polyisocyanates containing isocyanurate and/or biuret groups of formulae (IIa) and (IIb):

    OCN--(B)--[X].sub.n --NCO                                  (IIa)

and

    OCN--(B)--NCO                                              (IIb),

wherein B is ##STR22## [X]_(n) is: ##STR23## and n is 1-4, the weight ratio of (IIa) to (IIb) is (100 to 20) to (0 to 80) and 1 to 5 mole of the diamine (I) are reacted per the total of NCO groups in the compounds of formulae (IIa) and (IIb), at a temperature of 150°-190° C.; and (B) reacting the product with one mole of maleic or fumaric C₁₋₂ -(cyclo)aliphatic hydrocarbyl ester per NH₂ equivalent at a temperature of 50° to 70° C.
 9. A method of coating an article, comprising coating said article with a composition which comprises a low-viscosity (cyclo)aliphatic polyamine containing urea groups and having more than two amino groups, said (cyclo)aliphatic polyamine being obtained by reacting a diamine of the formula (I):

    R.sup.1 --NH--A--NH--R.sup.2                               (I)

wherein A is a (cyclo)aliphatic hydrocarbon radical having 2-16 carbon atoms which is optionally C₁₋₄ -alkyl-substituted, R¹ and R² are H or a radical of the formula ##STR24## wherein R³ is a (cyclo)aliphatic hydrocarbon radical having 1-12 carbon atoms, which is optionally branched, with polyisocyanates containing isocyanurate and/or biuret groups and of the formula (II):

    OCN--(B)--[X].sub.n --NCO                                  (IIa)

and

    OCN--(B)--NCO                                              (IIb),

wherein B is ##STR25## [X]_(n) denotes: ##STR26## and n is 1-4, the weight ratio of (IIa) to (IIb) is (100 to 20) to (0 to 80) and 1 to 5 moles of the diamine (I) are reacted per the total moles of NCO groups in the compounds of formulae (IIa) and (IIb).
 10. A method adhering a first surface to a second surface, comprising:(i) coating said first surface with a low-viscosity (cyclo)aliphatic polyamine containing urea groups and having more than two amino groups, said (cyclo)aliphatic polyamine being obtained by reacting a diamine of the formula (I):

    R.sup.1 --NH--A--NH--R.sup.2                               (I)

wherein A is a (cyclo)aliphatic hydrocarbon radical having 2-16 carbon atoms which is optionally C₁₋₄ -alkyl-substituted, R¹ and R² are H or a radical of the formula ##STR27## wherein R³ is a (cyclo)aliphatic hydrocarbon radical having 1-12 carbon atoms, which is optionally branched, with polyisocyanates containing isocyanurate and/or biuret groups and of the formula (II):

    OCN--(B)--[X].sub.n --NCO                                  (IIa)

and

    OCN--(B)--NCO                                              (IIb),

wherein B is ##STR28## [X]_(n) denotes: ##STR29## and n is 1-4, the weight ratio of (IIa) to (IIb) is (100 to 20) to (0 to 80) and 1 to 5 moles of the diamine (I) are reacted per the total moles of NCO groups in the compounds of formulae (IIa) and (IIb); and (ii) bring said second surface in contact with said coated first surface.
 11. The polyamine according to claim 1, having an amine content of 1-4 mmol/g, an isocyanurate group content of 1-6%, based on 126 g/mol, or a biuret group content of 1-5%, based on 98 g/mol, and a viscosity at 25° C. of 100-10⁵ mPa.s. 